:p *TIP* Most of you have an old inner tube lying around, or can get a non-repairable one, at no cost, from a bicycle repair shop. I can list several several hobby uses of these old tubes. 1. Punch a hole and make custom washers to be used under machine screws to waterproof screw holes made in your WTC. end cap or lid. 2. Cut 1/4-1/2" cross sections and make sturdy rubber bands, useful for holding AA batteries in battery cases. 3. Cut off the valve and modify for use as a vent valve, operated by a servo wheel cam. Or use in end cap to act as pressure relief valve.How many other uses can you think of? Does this remind you of practical uses for other easily obtainable or surplus items?

Hey Art good idea about the bike inner tubes i am trying a way of using them as balast tank bags for a 1/72nd Balaoany idea in general what a good starting point would be the tank can not be any wider than 2 1/8th " across it is the length estimate that i need as a starting point :)

:O You could just estimate the available space, cut the tube about an inch and a half longer than needed on each end, and glue, fold and clamp the ends by bending sheet metal (aluminum or brass) clamps around the folded ends. Take the stem out of the valve, and connect to your pump tubing. European inner tubes are smaller diameter than American, if that is what's needed.

Very original ideas Art. I never thought of using innertube valves. Heres one for you, I have always used an Aquarium Non return valve made for use on Air line.These items are inexpensive and 100% reliable..........regds U-Boater (Dave)

Uninterupted Sub Sailing? I got the idea from a guy in the army called Private Lake

:O Uboater,I have also investigated aquarium one-way check valves for prevention of flooding, and aquarium gang valves, for redirecting air flow in my ballast system. Never did need them, but they could be useful in different systems.Art